On Sunday, September 17, 2017 at 11:28:24 PM UTC+1, wrote:



double modelling? -- what's that about?


There is no budget in a Sun centered system for true/apparent motions or absolute/relative space and motion as Newton asserted. Any astronomer worthy of the name would simply recognize that a faster Earth overtaking the slower moving outer planets not only causes them to temporarily fall behind in view but also infers a stationary and central Sun -

https://apod.nasa.gov/apod/ap011220.html

The double modelling comes from a technical non sequitur where motions modeled from the Earth are apparent and modeled from the Sun are true -

"For to the earth planetary motions appear sometimes direct, sometimes
stationary, nay, and sometimes retrograde. But from the sun they are
always seen direct,..." Newton

The time lapse of the Earth overtaking Jupiter and Saturn and the easy way to interpret the motions obviates the need for the direct/retrograde loops which were the means by which Newton tried to create the impression of apparent motions seen from Earth -

https://apod.nasa.gov/apod/ap160915.html

Tricky I know but there is always the option to join the perpetually offended in this newsgroup as I go on to use more diagram, graphics and images to untangle theory from astronomy.